1. Field of the Invention
The present invention relates to the field of radiation imaging by scanning, particularly to a mobile inspection system for small vehicles.
2. Description of the Related Art
A vehicle carried mobile container/vehicle inspection system is necessary for inspection at customs, airfields, and railroad systems. The inspection system can obtain transmission images of contents contained in containers or vehicles by scanning the containers or the vehicles without opening the containers or the vehicles. The inspection system can find suspicious objects hidden within the container or the vehicles by analyzing the images.
The vehicle carried mobile container/vehicle inspection system is integrated on a trailer chassis to constitute a so-called scanning vehicle. In prior art such as a vehicle carried mobile container/vehicle inspection system (HCV MOBIEL SYSTEM) produced by German Smiths Heimann GmbH, an upright detector beam is configured as a foldable structure, and a horizontal beam has an end coupled with the upright detector beam and another end connected with a balance weight to balance the scanning vehicle.
However, a structure for balancing the vehicle in the above inspection system is complicated. It is necessary not only to ensure the scanning vehicle to be balanced in a transverse direction when the detector beam projects from the scanning vehicle, that is, in a state of inspection scanning, but also to ensure the scanning vehicle to be balanced when the detector beam retracts into the scanning vehicle. As a result, the entire balanced vehicle increases in weight, and has a weight over 20 t so that the trailer chassis used in the vehicle is one with three or four axles, thereby resulting in a high manufacturing cost.
In addition, the above system is complicated in structure due to the foldable upright detector beam. Moreover, a scanning height of the scanning vehicle is usually from 400 mm above the ground to the top of the scanned container or vehicle, so that the scanning vehicle can scan a container lorry other than a small vehicle with a low chassis.
In order to decrease the lowest scanning height of a scanning vehicle to enlarge an applicable range of the scanning vehicle, the applicant proposed a “combined mobile container inspection apparatus with a low target” in Chinese Patent No. 2715148Y. The apparatus can enlarge a scanning range and lower a scanning target. However, an upright detector beam of a scanning vehicle of the apparatus is foldable, and it is necessary that a radiation source rotates with the beam to accomplish a balance of the scanning vehicle in a transverse direction. Therefore, the scanning vehicle is disadvantageously complicated in structure and high in cost.